Initial pyrolysis mechanism and product formation of cellulose: An Experimental and Density functional theory(DFT) study

Qing Wang,Xinmin Wang,Nanhang Dong,Shipeng Sun,Hao Song,Shuo Pan

doi:10.1038/s41598-020-60095-2

Qing Wang, Xinmin Wang + Show 4 more

Open Access

https://doi.org/10.1038/s41598-020-60095-2

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Journal: Scientific Reports	Publication Date: Feb 27, 2020
Citations: 60	License type: open-access

Affiliation: Northeast Electric Power University

Abstract

In this paper, analytical pyrolyzer coupled with a gas chromatography–mass spectrometry set-up (Py-GC/MS) and density functional theory(DFT) theory was used to reveal the initial pyrolysis mechanism and product formation mechanism of cellulose pyrolysis. We demonstrated an experimentally benchmarked molecular simulation approach that delineates pyrolysis process of cellulose. Experimental results indicated that the cellulose pyrolysis products mostly incorporate levoglucosan (LG), glycolaldehyde (HAA), 5-hydroxyfurfural (5-HMF), and the like. The constituents of fast pyrolysis products of cellulose and cellobiose demonstrated the identical trend, although the contents of certain products are different. Laying the foundation of experimental analysis, the reaction pathways of four categories of cellulose pyrolysis were outlined using DFT theory; the pathways are those of generating LG, HAA, and 5-HMF and the dehydration reaction in the process of cellulose pyrolysis. Also, by comparing the energy barriers of various reactions, the optimal pathway of different reactions were summarized. The deduced cellulose pyrolysis reaction pathway opened up new ideas for studying the pyrolysis behavior of cellulose.

Highlights

In this paper, analytical pyrolyzer coupled with a gas chromatography–mass spectrometry set-up (PyGC/MS) and density functional theory(DFT) theory was used to reveal the initial pyrolysis mechanism and product formation mechanism of cellulose pyrolysis
LG has the highest content of the product in the pyrolysis process, and the content of LG is quite diverse in cellulose and cellobiose; this is consistent with the theory that the production of LG is related to the degree of polymerization of the cellulose chains
The experimental results reveal that LG and 5-HMF in cellulose pyrolysis products are significant products

Summary

Introduction

Analytical pyrolyzer coupled with a gas chromatography–mass spectrometry set-up (PyGC/MS) and density functional theory(DFT) theory was used to reveal the initial pyrolysis mechanism and product formation mechanism of cellulose pyrolysis. Bradbury[9] et al considered that cellulose macromolecules undergo intermediate physical and chemical changes, such as vitrification[10] or depolymerization[11] to degree of polymerization(DP) approximate 200, and it is transformed into designated products This is in line with the B-S model and has been studied in more depth. Some scholars have maintained that the production of light gases is indirectly related to the low temperature step or to anhydrous cellulose[15] These kinetics models have largely simplified the complexity of the primary and secondary reactions of cellulose pyrolysis. During the rapid pyrolysis process, hundreds of parallel or continuous pyrolysis pathways occur, thereby forming complex liquid products, including water, dehydrated sugar and carbonyl groups, compounds, phenols, furans, cyclopentanone, linear esters, linear alcohols, oligomers, etc. It is difficult to analyze the detailed mechanism through experiments

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